Magnetic amplifying system



Jan. 3, 1928. 7 1,654,932

R. A. HEISING MAGNETIC AMPLIFYING SYSTEM Filed June 29, 1922 2 Sheets-Sheet 1 R. A. HEISING ueum'xc munme srsml Filed June 29. 1922 4 2 Sheets-Sheet 2 Jan. 3, 192a 1,654,932

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Patented Jan. 3, 1928.

- UNITED "STATES RAYMOND A. HEISING,.

TRIO COMPANY, INCORPORATED, OF NEW YORK.

PATENT OFFICE.

OF 'MILLBURN, NEW JERSEY, LSSIGNOR n10 WESTERN ELEC- YORK, N. Y., A CORPORATION OF NEW MAGNETIC AMBLIFYING SYSTEM.

Application filed June 29, 1922. Serial ,No. 571,597.

This invention relates to magnetic amplifying systems and more particularly regenerative connections for such ampl1fiers to adapt them to produce; osc llations.

An object of the inventlon is to produce a stable oscillation source free from mov1ng parts and from elements which rapidly dc teriorate and require frequent renewal.

A more specific object is the provision of means involving the magnetic amplifier principle for converting direct'current energy into alternating current energy of any given frequency.

As is well known, any ampllfymg device may be made to produce sustained oscillations if its output circuit be so connected to its input circuit as to feed back thereto energy of the proper ampl1tude,wave form, and phase. The present invention relates to feed back circuits for amplifiers of the magnetlc t e.

l riefly described, the magnetic ampllficr consists of a core of magnetic material and two circuits each having a winding assoclated with the core. One of these, the controlling circuit, is traversed by direct current or varying controlling current and serves to produce in the core a magnetic flux of correspondingly varying density. As a consequence of the variations in flux density 1n the core, the higher frequency current traversing the other of the two circuits 1s subjected to a varying impedance and the energy changes produced 1n this higher frequency current may be much greater.t-han those of the controlling current (see Proc. Institute of Radio Engineers, April, 1916, vol. 4, No. 2, page 104). As thus far described the efl'ect of variations in the controlling current is to produce greater power variations in a high frequency current. If the high frequency current be rectified or otherwise demodulated it will yleld a comvponent of the frequency and waveform of the controlling current itself. It 1stherefore possible to utilize the magnetic amplifier to amplif control currents of any character such as speech or other signal currents.

According to the present invention high frequency currents are varied in accordance with control currents supplied to the controlling winding of a magnetic amplifier and are then rectified to produce amplified control currents. A portion of the amplified control current is then supplied through a suitable phase shifting network to the controlling winding to maintain the action. In order to maintain the average magnetization of the core at the proper density a steady field may be set up by direct current from a separate source or by the effective direct current component obtained in the rectifymg action. If the latter method be used the high frequency source becomes the. ultimate source of energy for the low frequency .control current and for the unidirectional polarizing current. The frequency of the control current or, in other words, of the sustain'ed'oscillations produced, may be readily determined by properly tuning the controlling circuit of the magnetic amplifier or by associating closely therewith a properly tuned circuit. I

The system just-described provides for the generation of a relatively low frequency oscillation by utilizing a prime energy source which produces waves of a higher frequency. The invention comprises, further, an arrangement whereby the high frequency wave may itself be generated within the system. To accomplish this, the low frequency wave generated as explained above may be amplified and impressed on a harmonic generator and amplifier from which a higher frequency wave may be derived. As many stages of harmonic generation as desired may be used, the output of the final stage being fed back to the magnetic amplifier to constitute the high frequency source above described. The system is, accordingly, sub-- stantially a magnetic amplifier combination in which an alternating current wave of any desired frequency may be derived ultimately from continuous current sources as the prime sources of energy.

r The. features of the invention which are considered novel are pointed out with parti'cularity' in the appended claims. The invention itself, however, together with fur- .ther objects and advantages may best be understood by reference to the following des'cription taken in connection with the accompanying drawings in which Fig.1 shows one modification of the invention in which the outputv circuit of a magneticamplifier system is connecteddirectly to the controllin circuit. Fig. 2 a modification of a detai of Fig. 1; Fig. 3 a modification of Fig. 1 in which a separate source of unidirectional polarizing current is provided; Fig. 6 4 a modification of the circuits between lines X and Y of Fig. 1 to provide for reversal of the alternating current instead of the direct current component; Fig. 5 illustrates diagrammatically the relations between the various currents and Fi 6 illustrates a s stem similar to that of ig. 1 but in which a separate source of high frequency is not required, the high frequency energy being derived from the system itself.

Referring to Fig. 1, the magnetic core 1 is shown associated with a controlling or input circuit winding 2 and divided or twopart output circuit winding 3. A source 4 supplies high frequency currents through condensers O, to windings 3 in parallel. The function of condensers C is explained on page 109 of the I. R. E. publication previously mentioned. They prevent the induction of low frequency current from the controlling circuit in the series circuit constituted by the coils 3 which would be short-- circuited except for these condensers. They are designed to have high impedance for the controlling current and low impedance for the high frequencycurrent. The two branches of winding 3 are magnetically relater to winding 2 in opposite senses, as illustrated. It follows that when the current through winding 2 tends toset up a flux in a given direction it will be aided by one of the windings 3 and opposed by the other. There will accordingly be no effective direct induction of low fre uency controlling energy from the input clrcuit to the circuit of source 4 and no direct induction of high frequency energy in the reverse direction. However, the rise and fall of the controlling current in winding 2,wll be attended by a correspondingly varying density of magnetic flux in the limbs of the core 1 and the effective permeability of the core for the high frequency flux set up by windings 3 will be varied in like manner. When the current in winding 2 is of such intensity as 5 to cause magnetic saturation of the limbs of the core 1 which areassociated with windings 3 the core will be effectively non-magnet'c for the high frequency flux and the impedance of windings 3 will become so low as to practically short circuit source 4.

When the current in winding 2 is small and the core l is not saturated the impedance" of windings 3 maybe extremel hi h. Preferably the average controlling ux is of substantiall the same order of magnitude as the big frequency flux and efiects .a-

change from substantially zero magnetization to complete saturation of the core.

The source'4 also supplies high frequency oscillations to ,a circuit LC which is connected in shunt to windings 3 and is tuned by meansof variable capacity-C so that the circuit as a Whole, including the generator is tuned to resonance with the high frequency oscillations when the current in controlling winding 2 is zero. At such times the source 4 supplies large amplitude oscillations to circuit LC. When the controlling current is a maximum the windings 3 operate to substantial y short circuit source 4 and the circuit LC as previously explained. Connected across a portion of inductance L 1s an output circuit path including a rectifier 5 of any desired type and the primary winding of an oscillation output transformer 6.

This path is directly connected to feed back energy to the input or controlling winding 2 through a network consisting of series blocking condensers C and G a series inductance L and two bridging choke coils 7 and 8 which are of extremely high impedance for alternating current. An electromotive force tending to force unidirectional current downwardly through the primary winding of transformer 6 will cause such current to traverse the path consisting of choke coil 8, winding 2 right to left, choke coil 7 and back through L and 5. A similarly directed alternating or pulsating current will take the path consisting of blocking condenser C winding 2 left to right, condenser 0 inductance L and back as before. Accordingly the pulsating current and direct current components of the output current supplied through rectifier 5 will be opposed in winding 2. The loop consisting of elements C 2, 0 L,, the upper portion of L, 5 and primary winding of transformer 6 is tuned to .the frequency of the oscillations to be generated and accordingly 1 determines the frequency of the controlling currents.

Suppose that source 4 is supplying oscillations to windings "3 and to circuit CL in parallel therewith and that the winding 2 is in some manner supplied with controlling current of the wave form illustrated at curve a, Fig. 5 in which the ordinates are intended to indicate only the absolute values of the current without regard to sign since the effect on'the impedance of windings 3 is independent of the direction of current. The impedance of windings 3 will accordingly vary as depicted by curve 6 of the same figure. The shunting action of windings 3 will cause the high frequency oscillations in the path L0 to vary as indicated at curve a which represents this high frequency current. The operation of the rectifier, if it is properly oled, will accordingly yield an amplified ow frequency or controlling current represented by curved. If the rectifier is oppositely poled the curve will be the same except as to sign and accordingly, as in curve a, the ordinates of the curve can be considered as indicating only the absolute curve (1 indicating the alternating current component if considered with reference to line e or the total rectified current, like curve b, if considered with reference to the zero axis 0. If reversed in direction with respect to coil 2 the unidirectional current component may be represented by the graph e This reversal is accompllshed 1n thec 1rcuit of Fig. 1 by the cross-connections including choke coils 7 and 8. The" net current in winding 2 is therefore the algebraic sum of the two currents represented by graphs 0! and e, and it will be obvious from inspection that it will have coincidence of maximum and minimum with the controlling current a. The initial impulse upon the input circuit C 2, 0,, when source 4 1s put in operation,'will set up oscillatory currents of the desired frequency in this tuned,

input circuit. The device will accordingly supply sustained oscillations of the controlling current frequency to the work circuit connected to the secondary winding of transformer 6. 7 On account of the amplification of the controlling current this current will build up during successive cycles until a stable value is reached as in the similar case of a vacuum tube oscillator. For the condition of steady operation, accordingly, the curves a and d would have approximately the same amplitude.

Inspection of curves a and d of Flg. 5

indicates that the necessary change in curve d may be alternatively accomplished by reversing the alternating, instead of the direct, current component. Circuits for accomplishing this function are shown in Fig. 4', which circuits may be substituted for thosebetween lines X and Y of Fig. 1. It is seen that the circuits of Fig. 4 result substantially by reversing the positions of the choke coils and condensers in the corresponding circuits of. Fig. 1. Since the condensers are removed from the linethe direct current component can flow unchanged through winding 2. On the other hand the choke coils 13 and 14 impede the flow of the alternating component and constrain it to flow through condensers C and 0,, with resulting reversal of this component.

indicated by corresponding letters.

Fig. 2 illustratesa modification in' which the source 4 is inductively connected to the output circuit of the amplifier.

In Fig. 3 the circuit arrangement is altered in two respects. A separate source 9 is used to supply steady unidirectional magnetizing current to windlng 2 through a choke coil 10 similar to coils 7 and 8. Blocking condensers O and 0 separate the path ofthis current from that of the direct current supplied by rectifier 5 and for which is provided a bridge return ath consisting of a choke coil 11. Thespu satingcomponent is supplied to windin 2 through a path comprising condenser a, winding 2, condenser C and a tuned loop O L The tuning of this loop substantially determines the frequency of the oscillations roduced. In both of the arrangements of igs. 1 and 3. the amplitude of the energy fed back and the resultant oscillations produced may be controlled by adjustment of the slider 12 along inductance L, thus varying the coupling. y

Fig. 6 illustrates an arrangement of cir-' cuits, involving the features shown in Fig. l, which avoids the necessity of a separate high frequency source, the high frequency current being derived from the system itself. This figure also illustrates a magentic amplifier system which makes use of the high frequency wave from this magnetic oscillator system. The block 0 represents a magnetic oscillator, which may be of the type shown in Fig. 1. The parts included between terminals AB and MN of Fig. 1 may be inserted in the system of Fig. 6 as This magnetic oscillator derives a high frequency current from circuit 15in a manner to be described later. It is assumed for convenience that the generated current supplied at the output terminals MN has a frequency of 10,000 cycles and that the high frequency current supplied at the input terminals AB has a frequency of 270,000 cycles. The 10,- 000 cycle product current from the oscillator is impressed on the harmonic producer GH which produces current which may have several harmonic frequencies, the third har- .monic (triple frequency) current of which is ing through the subsequent stages of har-v monic generation. Other stages of amplification may be inserted in the system where lected in each instance is governed by the desired frequency of the final roduct, 270,- 000 cycles in the case selecte The high frequency current from the last stage of harmonic generation is available for use in the l magnetic oscillator, as byv feeding it back to the oscillator by means of circuit 15, pre ferably after amplification by power amplifier AM It may be pointed out that in the oscilla- 2 or system, described the use of a separate igh frequency source is avoided. Accordingly the continuous current sources associated with the amplifiers and harmonic generators constitute the prime energy sources, as compared with the separate high frequericy source of Fig. 1. The oscillator therefore closely simulates the function of vacuum tube and other types of oscillators which comprise means for converting direct current energy into alternating current enpointed out-that applicants oscillator, in effeet, is a double frequency oscillator since in the case given either 10,000 or 270,000

cycle current may be derived therefrom.

The lower portion of Fig. 6 shows a circuit for utilizing the current from the magnetic oscillator. The circuit constitutes a means for radio transmission of a signal modulated high frequency wave. Since the wave from the magnetic oscillator provides the carrier wave, the higher of the two frequencies associated with the oscillator is used. v

The transmission system comprises means for using a mlagnetic amplifier for amplifying the signa frequency wave by as many stages as desired and a magnetic modulator for modulatin the high frequency wave from the oscil ator in accordance with the amplified signaling wave. The circuits comprising the magnetic amplifier AM,,, the tuned circuit 16, the high frequency source 17 and rectifier 18, are identically the same as the circuits comprising the low frequency amplifier combination illustrated in the-system of Figs. 1 and 2, comprising the core 1, controllin winding 2, and controlled winding'3 of ig. 1, and the tuned circuit and means for 1mpressing the high frequency wave shown 'in Fig. 2. For the last two elements the corresponding means of Fig. 1 may be-substituted. The signal frequency component of the rectified current is selected by filter F which may be of the type high frequency and the controlling or genergy of a desired frequency. It 1s furtherdescribed on ages 310 to 312, inclusive, of a' paper by Co p1tts,and Blackwell, Carrier current. telephon and telefira y, vol. 40, No. 4, Journal 0 the A. I. 1%., or similar selecting means and impressed on the succeeding magnet1c amplifier AM, which may 4 be identical in all respects to amplifier AM," This stage of amplification is followed by rectification and ..selection 1b elements 19 and F As many/stages of amplification ma be used as, desired, the circuit 17 furms ing the high frequency energy source for each stage. The signal frequency energy increases with each stage'of amplification. The final product of the amplifyin opera t1on is used in magnetic modulator OD to modulate the high frequency energy. This may be accomplished b any of'the convent onal magnetic modu ators, or specificaly, by the circuits of Fig. 1 omitting the rect1 fier and feed back, or in other words,

by circuits similar to those shown associated with amplifiers AM or AM, rectifier. The modulated hi h frequency wave may be radiated from aiieniia 20, but may equally well be impressed on a transmission line. 4

Throughout the description the oscillations of source 4 have been described as of erated oscillatioiis as of low frequencies. These terms are not used to define absolute frequencies or the orders of the'frequencies but merely to express-the general relation Y between them. 1

Itwill be readily appreciated-that this invention provides oscillation sources having very simple circuits, free from readily destructible elements, and capable of construction in a relatively large range of sizes.

7 Although the invention has been illustrated as embodied in certain specific arrangements it is to be understood that it is not limited to these but only by the scope of the appended claims.

What is claimed is:

1. In combination, a magnetic core, a lnglnfrequency' winding on said core, a source of high-frequency current for said winding, means for controlling said" high frequency current in accordance with a low frequency current comprising a second winding on said core, and means for deriving and feeding back energy in the form of the energy of a low-frequency current from said 1 high frequency circuit to'said second winding, said last means including tuning elements for rendering the feedback path to sand second winding resonant at saidlow frequency.

2. An oscillator comprising a magnetic amplifier having a high frequency controlled circuit and, a low frequency controlling circuit, means for feeding back from said high frequency circuitto said low frequency cir- 0 omitting the cuit ener of the same phase and wave form as t at supplied to said controlling circuit, and a utilization circuit for deriving low frequency current from said magnetic amplifier; I

3. A magnetic oscillator comprising in combination, a high frequency tuned circuit, a controlled winding, a high frequency source connected to said circuit, a controllin winding, magnetic coupling means for -sai windings whereby the impedance of combination, a high frequency circuit ineluding a controlled winding, a low frequency circuit including a controlling winding, magnetic means for controlling the flow of current in said high frequencycircuit in accordance with current in the low fre- (f uency circuit, and means coupling the high requency circuit to the low frequency,circuit, said low frequency circuit including a detecting means, tuning means, and means for reversing the direct current component of the detected current wave, said-reversing means comprising blocking condensers on either side of the low frequency circuit, and a pair of highly inductive, conductive bridging circuits connecting points on opposite sides of the circuit between the blocking condensers and the detecting means with cor-" responding points between the blocking condensers and the controlling winding, each bridging circuit being arranged to connect points on opposite sides of the low frequency circuit.

5. A magnetic oscillator comprising in combination, a high frequency. circuit ineluding a controlled winding, a controlling winding, a magnetic circuit con mon to said wmdlngs and arranged in such manner as to prevent energy transfer therebetween but to omit, the flow ofcurrent. in the control ed winding to be varied in accordance with the-variations of current in the controlling winding, a circuit coupling said high frequency circuit and said controlling windin and including a detecting means, and a clrcuit connected to said coupling circuit and-to said high frequency circuit and including a harmonic'generator and an amlifier for producing energy in said high quency circuit.

6. In combination, a circuit, a second cir cuit, a device coupling said circuits for producing in the second circuit a current the frequency of which is a harmonic of that in the first mentioned circuit; and a magnetic amplifier comprising a controlled winding connected in shunt to said second circuit, and a circuit in shunt to a portion of said second circuit and including detecting means, a controlling winding, and tuning'means; and means for impressing a portion of the current detected by said detecting means on the first mentioned circuit.

7 A system for producing oscillations of desired frequency comprising a circuit tuned to said frequency, a control winding energized therefrom, a load circuit, a source of relatively high-frequency energy, a highfrequency circuit connected to said source and including a winding, a magnetic circuit interlinking said two windings whereby variations in said first circuit produce variations in amplitude in the high-frequency current flowing in said high-frequency circuit, and means for derivin from said highfrequency circuit current 0% the said desired frequency and for applying said variations in part to said load circuit and in part to trolling and a controlled winding interlinked by a magnetic circuit, a high-frequency circuit having associated therewith a source of high-frequency energy, said circuit being connected to the, controlled winding, a circuit for supplying magnetizing direct cur rent and controlling alternating current of relatively low frequency to said controlling winding, whereby the high-frequency energy in said high-frequency circuit is varied under control of the current in said controlling winding, and a coupling circuit for deriving both said magnetizing current energy and said controlling current energy from.

said high-frequency circuit, said coupling circuit containing connections for applying the magnetizing and controlling current components to said controlling wmdingin proper phase to sustain the action of roducing said magnetizing and contro ing components from said high-frequency circuit.

9. A system for converting the energy of direct current into alternating current energy com using a magnetic amplifier system as de ned in claim 8, in which said source of high-frequency energy comprises a harmonic generator for convertin the energy of said direct current into hig -frequency energy, said harmonic generator having an input circuit supplied by said controlling alternating current and an output circuit associated with said high-frequency circuit for supplying high-frequency energy thereto.

In witness whereof, I hereunto subscribe my name this 27th day of June A. D., 1922.

RAYMOND A. HEISING. 

